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Sansui cd-x711 cd-player several problems!

Discussion in 'Electronic Repair' started by Erik, Dec 5, 2004.

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  1. Erik

    Erik Guest

    Hi!

    I have a sansui cd-x711 cd-player from the late 80's that have several
    problems.
    When a disc is loaded the lens from the pickup goes up and down a
    couple of times before reporting "no disc".

    After consulting another owner the startup sequence is supposed to be:
    drawer closes, and spindle/motor engages the disc, the disc starts to
    spin, the laser head tries to focus, then the disc starts to play.

    In my case the disc never starts to spin, the optical pickup that is
    of the linear tracking type (coils and magnets), whatever starting
    position is, doesnt move to the center. Both the motor and the coils
    are connected to a "RF/SERVO(f) board.

    What could the problem possibly be? Would be nice to get it going, it
    is a very nice unit. Dual power supplies, optical and coaxial outputs,
    balanced xlr outputs, and should have a very nice sound too.

    All help appreciated,

    /Erik
     
  2. Erik

    Erik Guest

    I forgot to mention that I checked all leads to pickup and motor, they
    are ok. However, there is no voltage at the terminal the motor
    connects to, probably the same thing for the coils at the
    trackingdevice connection. When it tries to focus, I can see a dim red
    light, apparently the laser is ok. There are a couple of boards in the
    unit, but in this case I think a part of the RF/SERVO(f) board is
    likely to be failing, the board is in two parts, the part where both
    the motor and tracking connects to is a vertical mounted little board
    on the larger mainboard, where the other cables from the pickup goes
    to.

    Hope you can help me on this one.

    Thanks in advance, Erik
     
  3. Your friend is wrong. It must focus FIRST, then spin the disc. Focus fails,
    no spin. Quite possibly a bad laser pickup. At the moment it "should" spin,
    try helping the disc spin by giving it a push. May take a couple tries. If
    it takes off, even spinning weakly, the spindle motor is bad. Sometimes they
    can be fixed by spraying the brushes with cleaner. Let us know and if this
    is the case maybe we can walk you through it.

    Mark Z.
     
  4. Most systems will spin the disc then focus (this certainly applies to all
    Philips units - in fact I've never seen a system that does otherwise).

    Usually the startup sequence is something like this:

    * Home the OPU (to the inside of the disc)
    * Attempt to spin the disc. New PC drives can tell by the acceleration of
    the spindle whether there is a disc present or not, although I doubt an 80's
    player will do this. If there is no disc present according to this check
    then stop.
    * While spinning turn the laser on and try and catch focus (apply a ramp
    signal to the focus actuators)
    * If focus is caught turn on radial feedback loops
    * Go and find the TOC etc...

    All players / drives will always home the OPU before trying to catch focus
    as the outside of the disc may contain no data (or it may be of the 8cm
    type).

    So by the sounds of your problem the motor, motor driver or motor driver
    supply section is bad.

    Martin.
     
  5. Actually, I was working on a Marantz (Philips made) today for a power supply
    problem and I am pretty sure that it focuses first then spins the disc like
    most of the other players that we work on. I think Mark is right on this
    one (as he usually is).

    Leonard
     
  6. Philips may have some exceptions. I was over-generalizing. Older players
    often have separate disc sensors, and many carousel changers do as well.
    The majority of single disc players, including CD-ROM drives, simply use the
    focus routine to detect the disc.

    Mark Z.
     
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